Composite cartridge for high velocity rifles and the like

Abstract

A plastic cased metal headed ammunition casing for high powered rifle cartridges is described in which the plastic case has a pressure regulating baffle or wall in the forward end thereof to regulate and control the development of chamber pressure movement of the bullet into the rifle barrel. The cartridge is charged with a given charge of powder and the cap or head securely fastened to the rearward portion of the plastic casing. The head provides sufficient resistance to the residual pressure after firing so that the cartridge can be used in rapid fire automatic weapons.

I claim: 
     
       1. A cartridge comprising: a plastic casing molded from a reinforced high impact plastic, said casing having a bullet end and a head end, said bullet end having a substantially cylindrical bullet receiving recess adapted to receive a bullet in a frictional engagement and having a pressure regulating front partition separating said bullet recess from a powder chamber, said pressure regulating front partition being molded integrally with said casing and having a frangible annulus positioned at the juncture between said partition and said casing, said annulus having a substantially uniform thickness around its periphery of from 0.010 to 0.020 inches whereby said partition resists removal thereof until a predetermined pressure is achieved in said chamber by an ignited powder charge;   an external interlock surface at said head end;   a cartridge head having a casing engaging recess at one end thereof and a primer receiving recess in the other end thereof, said casing engaging recess receiving said external interlock surface of said casing therein and extending toward said bullet receiving end around the outside of said external interlock surface and fairing with said casing, whereby pressure generated by detonation of a powder charge in said casing forces said casing outwardly into gas sealing relationship with said cartridge head casing engaging recess and whereby said head reinforces and prevents sidewall blowout of said casing during extraction of said cartridge from an automatic fire weapon.   
     
     
       2. The cartridge of claim 1 wherein said external interlock surface comprises a tapered surface having a first larger diameter at said head receiving end and a second smaller diameter at a location between said head end and said bullet receiving end, both of said diameters being smaller than the diameter of said casing. 
     
     
       3. The cartridge of claim 1 wherein the interior volume of said casing is sized to permit entry of a chosen powder sufficient to provide from 40,000 to 60,000 psi chamber pressure upon firing in a rifle chamber. 
     
     
       4. The cartridge of claim 1 wherein said pressure regulating front partition has on its rearward face a part spherical surface. 
     
     
       5. The apparatus of claim 1 wherein a swaging anvil is placed coaxially within the head receiving end of said casing before assembly of said head upon said interlock surface, said swaging anvil remaining within and becoming a part of said cartridge. 
     
     
       6. The apparatus of claim 1 wherein an adhesive bonds said casing and said head together. 
     
     
       7. The cartridge of claim 1 wherein the powder and the thickness of said frangible annulus are chosen to provide a chamber pressure of from 40,000 to 60,000 psi chamber pressure upon firing.